Field of the Invention
The present invention generally relates to turbochargers for internal combustion engines. More specifically, the present invention relates to an asymmetric double-entry turbine for a turbocharger in an internal combustion engine having an EGR system.
Background Information
Internal combustion engines such as gasoline engines and diesel engines are sometimes equipped with an exhaust gas turbocharger to boost power and to improve the efficiency of the engine. The exhaust gas turbocharger revolves a turbine by utilizing the pressure of exhaust gas from the internal combustion engine and also drives a compressor by the torque of the turbine for intake air charging the internal combustion engine. Internal combustion engines provided with an exhaust gas turbocharger and also with a bypass circuit that allows the outlet passage of the compressor and the inlet passage of the turbine to connect with each other are also known.
Internal combustion engines provided with the bypass circuit are designed to efficiently driving an exhaust gas recirculation system of the engine, or EGR system. An EGR system reduces the oxygen concentration in the intake air by partly circulating the exhaust gas to the intake air of the internal combustion engine and lowers the combustion temperature of the internal combustion engine in order to suppress the generation of nitrogen oxides (NOx) in exhaust gas. Internal combustion engines provided with the EGR system are so designed that the emission rate of NOx is observed and exhaust gas recirculation is made to take place when the emission rate becomes higher than a predetermined level.